1. Field of the Invention
The present invention relates to a character pattern forming apparatus which forms large character patterns for printing or display.
2. Description of the Related Art
A general label printer incorporates a font memory for storing a plurality of character fonts, a processor which reads character fonts from the font memory in correspondence with characters to be printed converts them into character patterns of a desired format, a buffer memory which stores the character patterns generated by this conversion, and a printing unit which is driven in accordance with the character patterns stored in the buffer memory. Normally, the character font is classified into the dot-matrix form and the outline form.
The dot-matrix form character font is represented by dots composing a character, whose distribution is in arrays of "1" or "0" in the matrix as shown in FIG. 1. On the other hand, the outline-form character font is represented by points which are sequentially connected to each other by straight lines in a frame as shown in FIG. 2 for making up outlines of a character, and a point which is located within the inner region of the outlines and given for coating the inner region. Each point is designated by a set of a point number, X-coordinate, Y-coordinate, and attribute which are expressed in numerical values. Table 1 shows an example of such an outline-form character font.
TABLE 1 ______________________________________ Point No. X-coordinate Y-coordinate Attribute ______________________________________ P1 25 20 1 P2 25 110 2 P3 50 110 2 P4 50 80 2 P5 65 70 2 P6 80 110 2 P7 100 110 2 P8 70 55 2 P9 105 20 2 P10 75 20 2 P11 50 50 2 P12 50 20 2 P13 25 20 3 P14 30 60 0 ______________________________________
In the attribute column in Table 1, "1" designates an original point, "2" an intermediate point, "3" a terminal point, of the outline, and "0" designates a point in the inner region of the outline, respectively.
For example, when issuing a cargo label for executing a door-to-door cargo delivery service, it is required that the destination or addressee be printed on the label in very large characters for quick visual identification. This demand can be materialized by setting a desired magnification rate on the printing format and magnifying character fonts read from the font memory according to the magnification rate. Nevertheless, when the available character fonts are in the dot-matrix form, the magnification brings about emphasizes on the steps formed in stairway oblique portions of the outline as shown in FIG. 1, thus visually degrading character quality. Although the outline-form character font is free from degradation of character quality, compared to the dot-matrix form, the outline-form character font requires much time for preparing the printing operation.
When establishing a condition in which extremely large characters must be printed out in a very short preparatory period without causing the character quality to be degraded, there is an idea to satisfy this condition by newly providing dot-matrix form character fonts solely for printing large characters in order that the new character fonts can be stored in a font memory together with ordinary character fonts prepared for printing normal characters. However, storage of large character fonts by itself requires a large memory. Furthermore, if these large character fonts are to be prepared for a variety of characters such as alphabet letters and numerals, the font memory needs to significantly expand storage capacity.